The present invention relates generally to switches, and more particularly, is directed to an overtravel switch actuator.
In a conventional click switch currently sold by the assignee of the present application, an actuator for the switch is comprised of a metal lever 10, as shown in FIG. 1, that is pivotally secured at one end 12 thereof to the housing for the switch by means of lever extension (not shown) formed thereat through which a pivot pin (not shown) extends. Metal lever 10 includes a convex intermediate bent portion 14 that is positioned above a circular hole in the housing and through which bent portion 14 is in contact with the upper surface of the click switch for actuating the same. The opposite end 16 of metal lever 10 is bifurcated and has a shaft (not shown) secured thereacross which rotatably receives a roller thereon. Since end 12 is at a fixed position on the housing, when the roller end 16 of lever 10 is depressed, lever 10 is pivoted about end 12 and bent portion 14 of lever 10 is forced down to actuate the switch, which emits a clicking sound as an audible indication of the actuation thereof.
However, a problem that results with such lever is that in many pieces of machinery in which this arrangement is used, the actuating machine part will force roller end 16 of lever 10 down to the metal housing during each actuation. Therefore, roller end 16 of lever 10 travels far past the point necessary to actuate the switch. As a result of this overtravel action, there is a tremendous amount of stress placed on lever 10, particularly around bent portion 14 thereof. Because of this, the life of lever 10 is severely reduced, that is, it fails in a shorter time than desired, by breaking at the high stress points.
FIG. 1 also shows the stress on lever 10 which is indicated by hatching to represent different colors. As shown, the red areas (4.72.times.10.sup.5 psi) 18 are the highest stress areas, followed by the yellow areas (3.3.times.10.sup.5 psi) 20, green areas (2.36.times.10.sup.5 psi) 22, light blue area (9.43.times.10.sup.4 psi) 24, and dark blue areas (no stress) 26. As shown, red areas 18 exist only at bent portion 14, and this is where there is failure that reduces the life of lever 10.